The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jun. 28, 1977
Filed:
May. 19, 1976
John Francis O'Neill, Boulder, CO (US);
Bell Telephone Laboratories, Incorporated, Murray Hill, NJ (US);
Abstract
A time-sampled port circuit is shown in which the charges impressed by the telephone set on the shunt capacitor of a low-pass filter associated with the port are passively sampled for transmission to the other port circuits, but which capacitor is impulse driven at a repetition rate equal to twice the cut off frequency of the filter with speech samples received from the other port circuits. By employing passive sampling in the transmitting leg instead of actual charge transfer, as in conventional resonant transfer design, the series inductor normally required in resonant transfer circuits may be omitted with the result that the port circuit switches may be integrated on one chip together with the digital circuitry for encoding and decoding the amplitude samples. Further, all need for amplifier gain adjustment in the port circuit is eliminated by applying different amplitude send and receive ramp signals to the encoder and decoder circuits. Transmission delay in a time division system employing the port circuit is compensated by delaying the onset of the receive ramp waveform.